Background: 'Re-infection' with Helicobacter pylori after eradication has been estimated to occur in 0-14% of patients, although most so-called 're-infections' occur within the first year following 'eradication' and many may actually be due to recrudescence of a temporarily suppressed infection.
Aim: To study the true re-infection rate, we have studied re-infection rates after eradication therapy by excluding the first year's data, minimizing the possible confounding effect of recrudescence.
Methods: All patients tested for H. pylori infection following eradication therapy between 1987 and 2004 were evaluated. Testing was carried out by urea breath test and gastric biopsy. Patients were included if they were found to be negative for H. pylori infection by testing at least 1 year following eradication and underwent at least one further test for H. pylori.
Results: 1162 patients met the inclusion criteria with median post-eradication follow-up of 3 years (1.5-14) including 4668 tests; 3319 years of follow-up were analysed. Thirteen cases of re-infection occurred (re-infection rate 0.4% per year).
Conclusions: This large study of H. pylori re-infection avoided cases of recrudescence by excluding the first post-eradication year. True re-infection is probably less common than previously thought.